Move the signal lever down (for a left turn) or up (for a right turn) to the stop position. The signal will self-cancel after the turn is completed.
If the indicator light continues to flash after a turn, manually return the lever to its original position.

The turn signal indicators in the instrument cluster flash according to the operation of the turn signal lever to show which signal is working.

NOTE
Turn and Lane-Change Signals
Lane-Change Signals and Three-Flash Turn SignalMazda 6 Owners Manual: Cruise actuator removal/installation
1. Disconnect the negative battery cable.
2. Remove in the order indicated in the table.
3. Install in the reverse order of removal.
Cover Removal Note
Unclamp the clips of the heater hoses at the front of the cover.
...
Mazda 6 Owners Manual: Abs (abs/tcs) hu/cm system inspection
System Inspection
Preparation
1. Verify that the battery is fully charged. With the ignition switch on,
verify that the ABS and BRAKE system warning lights goes out after 2.4
seconds.
2. If the lights stays on after 2.4 seconds, the ABS (ABS/TCS) HU/CM
detects a failure. Follow the troubles ...